Influence of acoustic phonon confinement on electron mobility in ultrathin silicon on insulator layers

Abstract

We show the importance of acoustic phonon confinement in ultrathin silicon-on-insulator inversion layers by comparing electron mobility calculated by the Monte Carlo method assuming a bulk acoustic phonon model (the usual procedure) with that obtained by using a confined acoustic phonon model developed in this work. Both freestanding and rigid boundary conditions are taken into account for the evaluation of the confined phonon dispersion in a three-layer structure. Mobility reductions of 30% are observed for silicon thicknesses of around 5–10nm when the confined acoustic phonon model is used.